The invention relates to a device for hot-air drying of a film printed in a rotogravure machine. As is well-known, a film emerging from a printing operation is wet with ink on its surface and therefore must be dried.
The prior art includes devices with this aim comprising a support frame which supports a single "chest" housing a blowing group composed of a plurality of slits envisaged for the feeding of hot air towards the film to be dried. In the frame there are also: a plurality of rollers mutually distanced one from the next and arranged along a predetermined course so as to favour introduction of the film, a plurality of idle running and support rollers, distanced one from the next and arranged along the said course to support the film and cause it to run, and movement means to draw the film.
Sometimes, because of defective film or excessive tension on the film during the passage through the rollers, the film itself breaks.
When this happens, the free portion, during the successive drawing phase, oscillates while moving and touches both the idler support and running rollers and other components of the blowing group, dirtying them with ink.
Consequently, the necessity arises of stopping the drying operation of the film both to clean the said dirtied components so that no following portion of the film is dirtied, and for the operation of reintroducing the film itself.
For the execution of this cleaning and/or introduction operation of the film, the prior art teaches the opening of the support structure and the translation of the entire blowing group by means of guides, or the rotation of all the group itself about a superiorly-positioned horizontal rotation axis.
In prior art machines the possibility does not exist of gaining access to the rollers and to the various ink-dirtied components in order to clean them, without performing the above-mentioned sliding or rotation operations.
Naturally, in order to effect the movement of the blowing group it is necessary to have a certain amount of space available, which brings about an arrangement of the different printing units with blowing groups which are used in the making of colour films.
Apart from the problems of the machine due to its size, the said sliding or rotation manoeuvre has been found to be difficult due to the fact that the support structure and the blowing group can have a combined weight of up to 12 quintals (about 2645 lbs.). For this reason, a support frame and movement organs have to be of adequate strength and power.
A principal aim of the present invention is substantially to resolve the prior art problems, overcoming the above-described difficulties by means of a device for the hot-air drying of film printed in a rotogravure machine.
A further aim of the present invention is to provide a device for the drying of a printed film which is simple to realize, functionally simple and compatible with the usual machines for such applications.
A still further aim of the present invention is to provide a device which is fixed and does not require the presence of support frames and movement organs to effect the cleaning of the components which perform the drying and drawing of the film.